Purpose: A growing number of schools are now implementing quality management systems (QMS). As a result, studies are being conducted to assess the educational benefits of these systems and their capacity to identify areas for improvement in school processes and performance. The purpose the present study is to assess the impact of ISO:9001 implementation on teaching-learning processes in the classroom, and in schools with at least three years' experience of applying this standard. Design/methodology/approach: To this end, a questionnaire was administered to a final sample of 2,185 subjects from 80 pre-school, primary and secondary education schools in the regions of Madrid, Castile and León, Andalusia and Valencia (Spain). Findings: The results show that ISO:9001 implementation yielded a higher than average impact on teaching-learning processes. Specifically, improvements were observed in the subdomains of tutorials, evaluation and classroom teaching methodologies as a result of implementing this QMS. Originality/value: This impact was higher in state-subsidized private schools in Valencia and Andalusia with over nine years' experience of ISO:9001 in schools with internal funding plans and in those with fewer than 29 teachers on the staff.